Dispensers are commonly provided in washrooms and similar facilities, in order to improve their overall environmental condition. In the past, various solid materials were utilized which sublimated, thereby dispersing a substitute odour for the odour found in public facilities. In order to enhance the dispersion of such sublimating materials, many suppliers developed powered fan devices which assisted in the dispersal of the sublimated material. Such devices are well known in the art, and an example is shown in U.S. Pat. No. 4,830,791 entitled “Odor Control Device”, which discloses a solid dispensing device.
More recently, odour control devices where a pressurized aerosol container is utilized have become well known in the art. Aerosol-type dispensing devices typically include a battery-powered motor that actuates the nozzle on the aerosol container on a periodic basis. These conventional dispensing devices have significant disadvantages. Aerosol cans require propellant gases, and whilst CFC-free propellants have been identified, these tend to require volatile organic compounds (VOCs), propanol, isobutanes and the like which are coming under increasing scrutiny. Several jurisdictions have introduced legislation aimed at reducing or elimination the unnecessary use of such chemicals.
It would therefore be desirable to deliver the scent directly, i.e. by evaporation or other dispersion of the scent composition itself, avoiding the need for carrier and propellant chemicals. This has been achieved for the home environment by SC Johnson, Inc. with the Glade® Wisp device, which uses a piezo element to disperse a scent formulation into the air by vibrating at high frequency while in contact with a small volume of the formulation. This aerosolises the formulation, dispersing it as required. However, such devices are problematic in that the volume of formulation that is in contact with the piezo must be closely controlled; if too large, the piezo does not resonate and the formulation is not dispensed. This requires the formulation to be delivered to a horizontally-disposed piezo element via a wick.